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United States Patent |
6,031,509
|
Kaitani
|
February 29, 2000
|
Self-tuning material for selectively amplifying a particular radio wave
Abstract
Self-tuning materials which can efficiently emit or receive radio waves in
spite of being simple in their construction and small in their dimension,
and are applied to patch antenna, wave directors or the like. Metallic
chips containing two or more kinds of ingredients which are distributed in
a layered, net-like or needle-shaped configuration, and an organic or
inorganic bonding material which is small in dissipation of electric power
under radio waves of high frequencies are mixed with each other, and are
pressurized under a high pressure while being highly electrified in the
direction perpendicular to the pressurizing direction to mold the metallic
chips and the bonding material in a plate-shaped configuration while being
heated.
Inventors:
|
Kaitani; Etsuko (Osaka, JP)
|
Assignee:
|
Suisaku Limited (JP)
|
Appl. No.:
|
029113 |
Filed:
|
February 18, 1998 |
PCT Filed:
|
September 11, 1996
|
PCT NO:
|
PCT/JP96/02594
|
371 Date:
|
February 18, 1998
|
102(e) Date:
|
February 18, 1998
|
PCT PUB.NO.:
|
WO97/10624 |
PCT PUB. Date:
|
March 20, 1997 |
Foreign Application Priority Data
Current U.S. Class: |
343/912; 428/328 |
Intern'l Class: |
H01Q 015/14 |
Field of Search: |
343/909,912
428/328
|
References Cited
U.S. Patent Documents
2840820 | Jun., 1958 | Southworth | 343/909.
|
4734140 | Mar., 1988 | Tzeng | 148/513.
|
5147718 | Sep., 1992 | Papoulias et al. | 428/328.
|
5366691 | Nov., 1994 | Takeda et al. | 420/548.
|
5789064 | Aug., 1998 | Valente et al. | 428/328.
|
Primary Examiner: Pascal; Robert
Assistant Examiner: Bettendorf; Justin P.
Attorney, Agent or Firm: Morrison Law Firm
Claims
I claim:
1. A self-tuning material for selectively amplifying a particular radio
wave emitted therefrom or received therein comprising:
a plurality of metallic chips densely coupled to one another;
each metallic chip containing at least two kinds of ingredients differing
in electrical charge;
each metallic chip being at least 40 mesh grain size;
a bonding material joining said metallic chips to one another; and
said self-tuning material having a porous metallic structure strengthened
with said bonding material, in which m internal resonant circuit is
generated by a small current going through said self-tuning material with
electromagnetic induction upon arrival of said particular radio wave.
2. A self-tuning material as claimed in claim 1 further comprising a coil
resonating with a desired frequency fixably mounted to said metallic
chips.
3. A self-tuning material as claimed in claim 1 wherein:
said metallic chips are each a hyper-eutictic aluminum-silicon alloy; and
said bonding material is a thermosetting resin.
4. A self-tuning material as claimed in claim 1 wherein said metallic chips
are densely coupled to one another on a plurality of connecting points
through surface diffusion.
5. A self-tuning material as claimed in claim 1 wherein the content of said
metallic chips is at least about 75 weight percent of said self-tuning
material.
6. A self-tuning material as claimed in claim 1 wherein:
said self-tuning material is formed in a plate-shaped configuration; and
said metallic chips are 10 to 40 mesh grain size.
Description
TECHNICAL FIELD
The present invention relates to self-tuning materials in a plate-shaped
configuration, which are small in their dimension and simple in their
construction, selectively emit or receive particular radio waves only and
absorb any unnecessary radio waves. The self-tuning materials are used in
the form of patch antenna, wave directors or the like in mobile or
stationary type radio or wireless communication devices for the use of a
microwave or millimetric wave band.
TECHNICAL BACKGROUND
The mobile type radio or wireless communication devices such as automotive
telephones, portable wireless telephones or the like are coming into wide
use, because they allow communication to be feasible regardless of time
and place. The propagational characteristics of radio waves differ
according to their frequencies, and the radio waves attenuate in their
propagational energy, and decrease in their reaches as their frequencies
are elevated. Therefore, the radio waves are difficult to propagate in
areas or places blocked by buildings or mountains when the radio waves
belong to the microwave or the millimetric wave band which is applied in
the field of the mobile radio or wireless communication. Moreover, in the
microwave or the millimetric wave band, the radio waves are damped in
their propagational energy owing to rain, fog or mist, and this denotes
that radio waves of high frequencies in the microwave or the millimetric
wave band come to approach light in their properties.
In this case, the foregoing trouble in which the radio waves are difficult
to propagate can easily be mitigated if the radio waves are strengthened
in their propagational energy to emit them. However, this countermeasure
can by no means be accepted if the radio waves cause a harmful effect on
the human body. Particularly, in polyclinics which are equipped with a
great number of electronic medical systems, the radio waves emitted cause
the electronic medical systems to malfunction, and this is a subject of
public discussion.
Therefore, it is completely out of the question to strengthen the
propagational energy of the radio waves to be emitted from the mobile type
radio or wireless communication devices.
In Japan, many of the mobile type radio or wireless communication devices
use radio waves of 100 MHz or more in their frequencies, and for example,
the automotive digital wireless telephones or the portable wireless
telephones employ radio waves chiefly of 1.5 GHz rather than 800 MHz in
their frequencies. Also, in a simpler portable digital wireless telephone
called PHS in Japan which stand for Personal Handy Phone System, a radio
wave of 1.9 GHz in the frequency thereof is applied.
The digital type radio or wireless communication is wider in the occupied
band width of frequency thereof than the analogue type radio or wireless
communication, and it is difficult to take many communicating channels for
the digital type radio or wireless communication. However, as compared
with the analogue type communication in which the communicating quality
suddenly deteriorates as the radio wave under reception becomes faint, the
digital type communication less deteriorates in the communicating quality
to some level of field intensity of the radio wave.
Generally, in the digital type portable radio or wireless telephones for
which a radio wave of 1.5 GHz in the frequency thereof is used, the
communicating unit area comprises small zones of 5 km to 10 km in radius,
and a base station is required to be located every three zones in their
intersecting points. For example, when the digital type portable radio or
wireless telephones which are operated in the district of Osaka Prefecture
are brought into that of Fukui Prefecture in Japan, such telephones
deteriorate in their communicating performance, and become finally
incapable of their communicating operation, because these two districts
are different service areas of the telephone company.
Also, the digital type portable wireless telephones can readily be affected
by surrounding noises, and within manufacturing factories and automobiles
in which there are a great deal of noises, it becomes frequently difficult
to allow the communicating operation of the digital type portable radio or
wireless telephones.
Moreover, the television uses radio waves of 30 to 3000 MHz in their
frequencies for the electric signals thereof, and the automotive
television deteriorates in its reception of the radio waves when, for
example, it is moved along the skirts of mountains.
The present invention is submitted to improve the foregoing disadvantages
of the mobile or stationary type radio or wireless communication devices
which use a microwave band or a millimetric wave band.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a self-tuning material
with densely coupled metallic chips which creates a resonance circuit upon
the introduction of a radio wave.
It is another object to provide a self-tuning material of metallic chips
coupled to one another and a coil connected thereto.
It is a still further object of the present invention to provide a method
for manufacturing a self-tuning circuit including mixing metallic chips
with a bonding material, applying a predetermined pressure to the
resultant mixture, heat molding the resultant mixture, and applying an
electric current through the resultant mixture in a direction orthogonal
to the application of the pressure.
An object of the present invention is to provide for a self-tuning material
which only amplifies a particular radio wave before it is emitted or after
it is received.
Another object of the present invention is to provide for a self-tuning
material in a plate-shaped configuration which achieves more efficient
amplification of a particular radio wave alone before it is emitted or
after it is received by connecting a resonance coil thereto.
Still another object of the present invention is to provide for a
small-sized self-tuning material which is applied to mobile radio or
wireless communication devices used for emission or reception of radio
waves in a microwave band or a millimetric wave band.
Still another object of the present invention is to provide for an
efficient method for manufacturing self-tuning materials of high
performance.
Yet another object of the present invention is to provide for a method for
manufacturing self-tuning materials while a high electric current of high
voltage is applied to them so that they are furnished with even or
identical electric characteristics on their whole surfaces.
Briefly stated, A self-tuning material has metallic chips of two or more
ingredients distributed in a layered, net-like or needle-shaped
configuration. A bonding material which has the property of having a small
dissipation of electric power under radio waves of high frequencies is
mixed with the metallic chips. The final mixture is pressurized and highly
electrified in directions orthogonal to one another.
These and other objects, characters and advantages of the present invention
will be more apparent to those engaged in the art from the following
description.
DISCLOSURE OF INVENTION
As illustrated in FIG. 1 of the accompanying drawings, a self-tuning
material of the present invention is a material in a plate-shaped
configuration, comprising metallic chips 2 which are densely coupled with
one another under the effect of surface diffusion, and respectively
contain two or more kinds of ingredients, and organic or inorganic bonding
materials which keep the metallic chips 2 joined to one another. The
metallic chips denote granular bodies or shavings of metal of a single
element or of an alloy, or the like. In FIG. 1, the self-tuning material 1
is a simple continuous body of the metallic chips 2, and this self-tuning
material may have both ends of a resonance coil 7 connected thereto as
shown in FIG. 2. Alternatively, the self-tuning material may be a porous
sintered body 8.
The resonance frequency of the self-tuning material 1 becomes still higher
when the metallic chips 2 in the form of granular bodies are smaller in
their diameters. As said granular bodies 2 are 10 to 30 mesh in their
grain size, for example, the self-tuning material 1 comprising the
granular bodies 2 can be applied to radio or wireless communication
devices which use radio waves of 300 to 3,000 Mhz in their frequencies.
The self-tuning material which comprises the granular bodies 2 of 30 to 40
mesh in their grain size can be applied to radio or wireless communication
devices employing radio waves of 1,700 to 5,000 MHz in their frequencies.
In general, the metallic chips 2 are alloys having ingredients 3 and 4 as
is apparent from FIG. 1 or 3. The metallic chips 2 may comprise in mixture
a plurality of chips of different ingredients.
In the metallic chips 2, it is preferable that the ingredients 3 have a
small amount of ingredients 4 distributed over them in a layered,
net-like, needle-shaped configuration or other similarly shaped
configuration. The ingredients 3 and 4 are required to differ in their
electric charges.
As the materials for the metallic chips 2, a hyper-eutectic
aluminum-silicon alloy or a carbon steel (Fe--C) may be exemplified. That
is to say, the ingredients 3 may be aluminum, iron or the like and the
ingredients 4 may be carbon, silicon or the like. As the materials for the
metallic chips 2, other metallic alloys such as cast iron may be used,
which contain three or more kinds of ingredients 3 and 4 including iron,
carbon, silicon, manganese and other elements. However, it is not
preferable that any alloy containing metal element having large electric
resistance as a material for the metallic chips.
In order to form an applicable chip 2, a certain kind of metallic chip may
be arranged to be electroplated with other metal so that two or more kinds
of metal are disposed in a layered configuration. In this case,
vacuum-evaporation coating technique can be substituted for
electroplating.
In the self-tuning material 1, the organic or inorganic bonding materials
which fusion-couple the respective metallic chips 2 with one another is
desired to be an insulating material which is small in power dissipation
even if it is subjected to a high frequency. For example, a thermosetting
resin such as polyurethane, epoxy, tetrafluoroethylene (trade mark:
TEFLON), polyester, phenol, diallyl phthalate resin and the like, and a
ceramic pulverized body, for example, cement powder, glass powder and the
like can be exemplified as the bonding materials. When the self-tuning
material 1 is operated under a working atmosphere of a high temperature,
the bonding materials are desired to be made in the form of porous
sintered bodies made from cement powder, glass particles or other ceramic
granular bodies.
In a manufacturing apparatus 10 of the self-tuning material 10, as
illustrated in FIG. 4, a pair of electrode plates 12, 12 which are
identical in their surface areas are opposedly disposed on a horizontal
ceramic plate 11 to form a molding frame 14. As shown in FIG. 5, one of
the electrode plates 12 has an electric wire 15 connected to a side end
thereof from a low-voltage transformer (not shown), and the other
electrode plate 12 has an electric wire 16 joined to an opposed side end
thereof.
In order to manufacture the self-tuning material 1, a plate of mold
releasing material 20, for example, newspaper is placed on the bottom
surface of the molding frame 14, and thereafter, the metallic chips 2 and
the bonding materials are evenly put into the molding frame 14 after being
sufficiently mixed with each other. Moreover, a second sheet of mold
releasing material 20 is laid onto the metallic chips and the bonding
material which have been put into the molding frame 14.
The self-tuning material thus obtained is considered to be of sufficient
porosity provided that the content of the organic or inorganic bonding
materials is about 10 weight % or less of the total weight thereof. When
said content is 10 to 25 weight %, the self-tuning material 1 is decreased
in the electric conductivity and air permeability thereof although it is
provided with small pores. Therefore, the content of the metallic chips 2
in the self-tuning material usually is about 75 weight % or more, and is
preferably about 90 weight % of the total weight thereof.
Within the molding frame 14 of the manufacturing apparatus 10, the metallic
chips 2 and the bonding materials are desired to be 4 to 70 mm in their
overall thickness before they are pressurized. In operation, a pressing
die 17 is lowered into the molding frame 14, and keeps lowered until the
electric current which flows through the molding frame 14 becomes 2,000 to
6,500 amperes, to allow the pressing die 17 to pressurize the metallic
chips 2 and the bonding materials generally under pressure of 210
kg/cm.sup.2 to 340 ton/cm.sup.2. This pressurizing operation is continued
for a predetermined period of time. As the electric current flowing
through the molding frame 14 keeps substantially constant in the amperage
thereof, the molding thus obtained, which is in effect the self-tuning
material 1 is brought out of the molding frame. This self-tuning material
1 thus obtained is cut to a variety of dimensions according to usage
thereof. For example, it is desired to be generally thinly sliced when the
self-tuning material 1 is used for a portable wireless telephone. It is
preferably cut to greater size when it is applied to a transmitting or
receiving apparatus which uses a radio wave of a lower frequency as
television.
In the manufacturing operation of the self-tuning material 1, if it is not
produced in the form of a sintered body, the material heating temperature
may be lower, and may be such as about 80 to 150.degree. C. Also, the
electric current fed through the molding frame 14 may be relatively low in
the ampere thereof.
When the metallic chips and the bonding materials are pressurized in the
molding frame, an electric current of high ampere and great voltage is
applied through the metallic chips and the molding frame within the
molding frame. The reason for this is that the electric current can break
or rupture the surface film of the resin, namely, the bonding material at
each of the junctures of the metallic chips 2, thereby achieving the
equalization of the quality of the self-tuning material thus obtained.
As illustrated in FIG. 1 or 3, the self-tuning material 1 is heated under
high pressure, whereby the surface diffusion of each metallic chip 2
increases the junctions of the metallic chips 2 to one another, and
provides the interiors of a connecting layer 5 with a great number of
small pores 6. In each metallic chip 2 of the self-tuning material 1 or 8
as illustrated in FIG. 1 or 3, one ingredient 3 has the compositional
element Si of the other ingredient 4 inserted in a belt-shaped
configuration in the aluminum matrix thereof, and as a result, the
metallic chip 2 is furnished with a layered form of combinational
construction of the elements Al and Si. This allows the molten bonding
materials to flow into the spacings between every two metal chips in
contact with each other, to form the resinous connecting layer 5 furnished
with a great number of small pores 6 as a whole.
The self-tuning material 1 is presumed to be subjected to the following
electric operation. The self-tuning material 1 is constructed in a
net-shaped configuration such that the respective metallic chips 2 are
closely joined with one another, and for this reason, an arrival of a
radio wave at the self-tuning material 1 allows a slight amperage of
electric current to occur therein through the electromagnetic induction.
Between the ingredients 3 and 3 or between the ingredients 4 and 4, this
electric current of a slight amperage flows without generating any
electromotive force, while on the other hand, the electric current creates
electromagnetic force when it flows between the ingredients 3 and 4 which
differ in their electric charges. The electric current thus spreads to the
whole of the self-tuning material 1. As a whole, the self-tuning material
is provided with a very great number of electric paths between the
ingredients 3 and 4 to allow the electric current to flow. As a result,
the self-tuning material 1 has electromagnetic force still more increased,
and it is subjected to considerably great electromagnetic force as a
whole.
In the self-tuning material 1, since the respective metallic chips 2 are
closely joined to one another, the electric current flows through the
self-tuning material while widely spreading out over the self-tuning
material. That is to say, the self-tuning material 1 is equivalent to a
resonance circuit having a coil, a resistor, and a condenser in series
connected thereto.
In a high-frequency band in which resonance is occurable, the self-tuning
material 1 executes selective amplification on a particular frequency of
radio wave, and absorbs faint radio waves of other frequencies. This
operation of the self-tuning material becomes still more effective when it
has the resonance coil 7 connected thereto.
In the case that the self-tuning material 1 is used as a wave director of a
portable wireless telephone, said self-tuning material is cut to size of,
for example, 14 mm in length, 24 mm in width and 4 mm in thickness, and
the self-tuning material of this size is attached to a digital type
portable wireless telephone adjacent to an antenna 31 thereof as shown in
FIG. 6. The metallic chips 2 in the self-tuning material 1 include a great
number of linear portions through which a slight amperage of electric
current flows, to form radio waves which are slightly smaller in
wavelength than half wavelength of radio waves emitted or received through
the self-tuning material, and as a result, the self-tuning material 1
achieves amplification of radio waves which are to be emitted or have been
received through the self-tuning material 1.
The self-tuning material 1 includes, for example, the connecting layer 5
which functions as a dielectric layer, and also, the aluminum elements of
one ingredients 3 and the silicon elements of the other ingredients 4,
which both ingredients 3 and 4 allow induced currents to flow through
them, are located in a layered configuration in the self-tuning material
1. Moreover, the self-tuning material 1 discontinuously includes air of a
low dielectric constant in a great number of small pores 6 therein.
In order to use the self-tuning material 1 as a patch antenna of automotive
television, the self-tuning material 1 is cut so as to be 10 mm in length,
30 mm in width and 5 mm in thickness, and it is fitted with a connector
means (not shown) to be connected to the metallic chips buried therein. In
order to attach the self-tuning material 1 to the interior of an
automobile, the self-tuning material 1 is fixed on an upper portion or
other similar suitable portion of, for example, the windshield or
windscreen, and the connector means has an electric feeder wire connected
thereto from the automotive television.
In the self-tuning material 1, the antenna is presumed to function for a
wide frequency band of radio waves, because a great number of metallic
chips 2 are extremely densely coupled with one another in the interior of
said self-tuning material, whereby an electric connection is extended
substantially evenly over and on a plane on each metallic chip. When a
variety of flowing of electric currents occur through aluminum contained
in one ingredients 3 of each metallic chip, a great number of distances
are created over which the electric currents flow, to form radio waves of
length which is equivalent to half wavelength of the radio waves to be
emitted.
Also, in the metallic chips 2 which are not electrically connected within
them, the electric currents are allowed to flow by using an
electromagnetic induction, and the distances over which the electric
currents flow are great in number, to create radio waves which are
slightly smaller in length than a half wavelength of the radio waves to be
emitted. This can be presumed to be the function of such metallic chips in
which they serve as wave directors of the antennas.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic sectional view exemplifying the self-tuning material
in a plate-shaped configuration according to the present invention, in
which component metallic chips are enlargedly depicted more schematically
than the real metallic chips;
FIG. 2 is a schematic sectional view showing a modification of the
plate-shaped self-tuning material of FIG. 1, which has a resonance coil
connected thereto;
FIG. 3 is a schematic sectional view showing a modification of the
self-tuning material, in which it is made of aporous sintered body, and
the metallic chips are enlargedly illustrated more schematically than the
real metallic chips;
FIG. 4 is a schematic sectional view showing a manufacturing apparatus for
the self-tuning material of FIG. 1;
FIG. 5 is a schematic plan view of the manufacturing apparatus of FIG. 4;
FIG. 6 is a schematic perspective view exemplifying a working state of the
self-tuning material of FIG. 1, and
FIG. 7 shows an operating experiment employing the self-tuning material
according to the following Example 1, FIG. 7a is a graph of the
frequencies of the radio waves emitted by a portable wireless telephone
which is fitted with the self-tuning material and FIG. 7b is a graph of
the frequencies of the radio waves emitted by a portable wireless
telephone which is not fitted with the self-tuning material.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will now be understood by reference to the following
examples, however, it will be understood that the present invention is not
limited by the following examples, and variations may be made by one
skilled in the art without departing from the spirit and scope of the
invention.
EXAMPLE 1
As metallic chips 2, shavings of a hyper-eutectic aluminum-silicon alloy
including 12% of silicon were used, which have 10 to 30 mesh in the grain
size. 95.5 weight % of the shavings and 0.5 weight % of iron powder were
mixed and 4 weight % of an epoxy resin in liquid form as a bonding
material was added, to obtain viscous mixture.
In a manufacturing apparatus 10 shown in FIG. 4, a pair of electrode plates
12, 12 in a rectangular-shaped configuration which are identical in their
surface areas were opposedly located on a horizontal ceramic plate 11 of
heat resistance. As shown in FIG. 5, a pair of heat resisting side walls
13, 13 were disposed on these electrode plates 12, 12 such that the side
walls 13, 13 intersect with the electrode plates 12, 12 at right angles,
to form a molding frame 14. The molding frame 14 has a bottom area of 300
mm by 600 mm and depth of 50 mm.
As is apparent from FIG. 5, one of the electrode plates 12, 12 had an
electric wire 15 connected to a side end thereof from a transformer (not
shown) for the use of low voltages, and the other electrode plate 12 had
an electric wire connected to an opposite side end thereof. A horizontal
ceramic plate 11 had a thermocouple inserted therein, to allow the molding
frame 14 to be measured in an inside temperature thereof.
As is shown in FIG. 4, newspapers 20 of 150 grams in weight were flatly
placed on the bottom surface of the molding frame 14. Thereafter, the
viscous mixture was put into the molding frame 14 such as to be 4 mm in
thickness, and this mixture was leveled on the surface thereof. Moreover,
newspapers 20 of the same kind as above were flatly placed on the surface
of the mixture.
A ceramic pressing die 17 was lowered on the surface of the mixture within
the molding frame, while the electric power was turned on to electrify the
interior of the molding frame. The pressing die 17 kept lowered until the
electric current flowing through the molding frame increases to 20 amperes
to a maximum of 3,000 amperes, to allow the mixture to be pressurized. The
pressurization was continued under pressure of 120 t/cm.sup.2 for 1
minute, and the electric current flowing through the molding frame 14 was
gradually decreased, when the mixture was heated to 80 to 120.degree. C.
As the molding operation was thus finished, the pressing die 17 was lifted
to remove the molding out of the molding frame 14, and then the molding
was cooled.
The molding thus obtained was cut to plate of 14 mm in length, 24 mm in
width and 4 mm in thickness. Moreover, this molded plate was
urethane-coated into a self-tuning material of 15 mm in length, 25 mm in
width and 5 mm in thickness.
In order to use this self-tuning material as a wave director of a portable
radio or wireless telephone, the self-tuning material was longitudinally
pasted on a telephone extremely adjacent to an antenna 31 thereof by using
adhesive tape which has adhesives applied to both sides thereof, as shown
in FIG. 6.
For example, the attachment of the self-tuning material to the digital type
portable wireless telephone 30 for the use of radio waves of 1.5 GHz in
their frequencies allows the telephone 30 to remain feasible of
communication without any deterioration in the phonetic quality even if
the telephone is moved from Osaka Prefecture to Fukui Prefecture in Japan.
Also, the digital type portable wireless telephone fitted with the
self-tuning material can provide for an ordinary level of communication
even within the manufacturing factories or automobiles in which there is a
great deal of noises.
EXAMPLE 2
The shavings of a hyper-eutectic aluminum-silicon alloy, as used in Example
1, was also employed as the metallic chips 2, and were mixed with a
powdery urethane resin (10% in content). The mixture thus obtained was 800
grams in the weight thereof.
In the manufacturing apparatus shown in FIG. 4, newspapers 20 were flatly
placed on the bottom surface of the molding frame 14. Thereafter, 800
grams of the mixture obtained as described in the foregoing was put into
the molding frame 14, and was leveled on the surface thereof. Moreover,
newspapers 20 of the same kind as described in the foregoing were also
flatly laid on the surface of the mixture.
A ceramic pressing die 17 was lowered onto the surface of the mixture
covered with the newspapers within the molding frame, while the electric
power was turned on to electrify the interior of the molding frame. The
pressing die 17 kept lowered until the electric current flowing through
the molding frame increases to about 6,000 amperes, to allow the
pressurization of the mixture. For the pressurization, pressure of 70
t/cm.sup.2 was exerted upon the internal mixture of the molding frame, and
then this mixture was rapidly heated to 1,200.degree. C. Thereupon, the
electric current which flows through the molding frame was gradually
decreased. The reason for this is that the Al--Si alloy in a highly heated
condition was oxidized on the surface thereof with the atmospheric oxygen,
to increase the electric resistance thereof. After the mixture had been
rapidly heated to 1,200.degree. C., the ceramic pressing die 17 was lifted
to remove the sintered molded plate out of the molding frame 14, and then
the molding was cooled.
The sintered molded plate thus obtained was cut to size of 10 mm in length,
30 mm in length and 5 mm in thickness, and a connector means (not shown)
was connected thereto to use it in the form of a patch antenna for an
automotive television. The sintered molded plate, which is in effect the
self-tuning material was an upper inside portion of the windshield or
windscreen of an automobile, and had an electric feeder wire connected to
the connector means thereof from a television loaded on the automobile.
This automotive television fitted with the self-tuning material remains
satisfactory in the reception thereof, when it is moved along the skirts
of mountains or into tunnels of small distances together with the
automobile on which the television is loaded. Also, this television
remains substantially unchanged in the reception thereof even if the
automobile having the television loaded thereof is changed in the
advancing direction thereof.
This patch antenna allows the television to be better in the reception
thereof under a ultrahigh frequency of small wavelength of televisual
radio waves than under a very high frequency of televisual radio waves.
Although being not illustrated, the self-tuning material 1 cut to size of
4.5 mm in length, 10 mm in width and 2.5 mm in thickness was effective to
improve the performance of an analogue type cordless telephone for the use
of a small amperage of electric current, which is usually not more than
100 meters in the communication coverage thereof. In this case, the
self-tuning material was pasted on each of the parent machine and the
child machine which together form a set of the analogue type cordless
telephone.
This cordless telephone was experimentally found to allow communication
over a linear distance of nearly 300 meters, when it was moved into a
concrete building from a wooden house.
In the analogue type cordless telephone fitted with the self-tuning
material, communication was thus feasible over a greater distance than in
the analogue type cordless telephone which is not equipped with the
self-tuning material. This is true of a simple type portable telephone
called PHS (Personal Handy Phone System) in Japan which is a digital type
cordless telephone.
EXAMPLE 3
The sintered molded plate obtained in Example 2 was cut to size of 4.5 mm
in length, 10 mm in width and 2.5 mm in thickness, and as shown in FIG. 2,
it has both ends of the coil 7 connected thereto, which resonates with
frequencies of 700 to 900 MHz. This coil functions to achieve greater
amplification of radio waves to be emitted through the self-tuning
material, and attains more effective absorption of other radio waves of
feeble frequencies.
In order to use this self-tuning material as a wave director for emitting
the radio waves from a digital type portable wireless telephone, the
self-tuning material was longitudinally pasted on the digital type
portable wireless telephone 30 extremely adjacent to the antenna 31
thereof by using adhesive tape which has adhesives applied to both sides
thereof.
As any of portable wireless telephones was arranged to have this
self-tuning material internally attached thereto by a manufacturer
thereof, it was more effective to improve the performance of any portable
wireless telephones.
EXAMPLE 4
In order to obtain a modified sintered body of porosity, 17 kg of shavings
of cast iron (specified as "FC-25" in the Japanese Industrial Standard
which contains carbon of about 3.5%, silicon of about 2.5%, and manganese
of about 0.5%) were used as the metallic chips. The shavings were mixed
with powdery epoxy resins of 1 kg which serve as the bonding material. The
mixture thus formed was subsequently treated as described for Example 2
except that the electrification of the molding frame was brought to a stop
when the internal temperature of the molding frame 14 became constant in 1
to 2 minutes after the metallic chips and the bonding materials had been
pressurized within the molding frame. The pressurization was continued
until these molding materials are formed into a molded plate of
predetermined thickness, and thereafter, the pressing die 17 was lifted to
remove out of the molding frame the sintered plate thus molded.
The molded sintered plate thus obtained was left in the atmosphere to cool
it after being removed out of the molding frame. This plate is resistant
against heat, and is light in weight because it is porous.
In the place of the cast iron shavings, shavings of plain steel (carbon
content: 2.5 to 4.5%) may be used as the metallic chips, and glass powders
of 1 mm in their average diameters or ceramic powders may be substituted
for the epoxy resin as the bonding material.
Next, in order to demonstrate the operation and effect of the present
invention, the following experiments were executed by using the
self-tuning material manufactured in Example 1.
Experiment 1
A single piece of the self-tuning material was affixed to a digital type
portable wireless telephone for radio waves of 800 MHz in frequency band.
In this case, the definite position for affixing the self-tuning material
is as shown in FIG. 6.
This portable telephone was measured in the emitted radio waves thereof for
300 milliseconds in an anechoic room for radio waves, and for comparison,
a portable wireless telephone which was not fitted with any self-tuning
material was also subjected to measurement of radio waves emitted thereby
in the same anechoic room. As a result, the portable telephone fitted with
the self-tuning material proved to emit radio waves of 755.135 MHz in
their frequencies. FIG. 7a is a graph which shows the frequencies of the
radio waves emitted by the portable wireless telephone fitted with the
self-tuning material. FIG. 7b also graphically shows the frequencies of
the radio waves emitted by the portable wireless telephone which is not
fitted with the self-tuning material.
From FIG. 7a it is understood that the portable wireless telephone fitted
with the self-tuning material has a peak value of 49.90 dBuV in the
frequencies of the radio waves emitted thereby, and this peak value is
apparently superior to a peak value of 43.80 dBuV in the frequencies of
the radio waves emitted by the portable wireless telephone which is not
mounted with the self-tuning material.
FIG. 7a also shows that in the portable wireless telephone fitted with the
self-tuning material, the frequencies of the radio waves emitted thereby
remains constant, and the radio waves emitted thereby are stabilized in
their condition, while on the other hand, the portable wireless telephone
having no self-tuning material attached thereto creates radio waves of
frequencies which are approximate to the particular frequencies to be
intended to be emitted, thereby causing unstable condition of radio waves
emitted.
Experiment 2
A simple wave measuring instrument ("Trifield Meter") was used to conduct
the following experiment.
A portable wireless telephone (trade mark: MITSUBISI DII) was fitted with a
single piece of the self-tuning material adjacent to the speaker portion
thereof. The amount of electromagnetic waves which leaked from the speaker
area of this telephone while it was in operation was measured, and it was
found to be approximately 1 mG.
On the other hand, with the self-tuning material removed from this
telephone, the leakage of electromagnetic waves from the speaker area
thereof measured 100 mG while it was in operation.
Similarly, a different portable wireless telephone (trade mark: PANASONIC
DP141) fitted with the self-tuning material was measured in the leakage of
electromagnetic waves from the speaker area thereof while it was in
operation, and this leakage was found to be 10 mG to 15 mG, whereas this
portable wireless telephone without any self-tuning material measured 100
mG or more in the of electromagnetic waves from the speaker area thereof
while being in operation.
These experimental results show that the self-tuning material produce an
absorbing effect upon radio waves which are unnecessary to allow the
portable wireless telephone to maintain high quality of communication in a
high-frequency band of radio waves.
Experiment 3
A voltmeter was used to perform the following experiment. A portable
wireless telephone (trade mark: PANASONIC DP141) was fitted with a single
piece of the self-tuning material adjacent to the speaker portion thereof.
In this telephone, voltage generated by means of the leaked
electromagnetic waves measured +0.1 to +0.6 mV. On the other hand, in the
same telephone free from the self-tuning material, the leaked
electromagnetic waves were found to create voltage of -1 to +3.6 mV.
These experimental results denote that the self-tuning material according
to the present invention has effects in which leakage of electromagnetic
waves from the portable wireless telephone is decreased, and the radio
waves emitted from the telephone are increased.
Industrial Applicability
Although the self-tuning material of the present invention is simple in the
construction thereof, and is small in the dimension thereof, this
self-tuning material forms a resonance circuit to particular radio waves
to perform selective amplification upon them, whereby the self-tuning
material can be used in the form of a patch antenna or a wave director for
radio or wireless communicating devices for the use of a microwave band or
millimetric wave band of the radio waves.
Also, this self-tuning material is a considerably small-sized plate, and
therefore, the attachment thereof to a mobile type communication device
scarcely becomes an obstacle to a user of the communication device.
Moreover, from the viewpoint of the application of the self-tuning
material to the patch antenna, it is an advantage that a limited small
space suffices for mounting the self-tuning material to the communication
device. In addition, even if the direction in which radio waves of a
microwave band or millimetric wave band are emitted or received does not
always remain constant, the self-tuning material is convenient in that it
is not required to be changed in the angle at which it is located in a
portable wireless telephone, each time the direction in which the radio
waves are to be emitted or have received alters when, for example, the
self-tuning material is moved together with an automobile in which a
portable wireless telephone fitted therewith is loaded.
As the self-tuning material of the present invention is attached to a
mobile type communication device, the communication device can execute
radio or wireless communication without strengthening the radio waves to
be emitted thereby even if the antenna thereof is not stretched.
By connecting a resonance coil to the self-tuning material, this
self-tuning material more enhances amplifying operation thereof for
particular radio waves to allow the communication device fitted therewith
to conduct communication under feeble radio waves, whereby it is feasible
to enlarge band width of frequencies in which radio or wireless
communication can be executed in an area of an identical number of radio
stations.
This self-tuning material is free from any influence of an increase in the
amount of radio waves emitted by a radio or wireless communication device,
and therefore, it is unnecessary to allow for an evil effect of an
increased amount in radio waves emitted thereby upon human bodies.
In a band of high frequencies such as a microwave band or millimetric wave
band, the self-tuning material according to the present invention
selectively amplifies radio waves of particular frequencies, and absorbs
radio waves of other frequencies than particular frequencies, to stabilize
the condition of the radio waves emitted or received through the
self-tuning material.
As the self-tuning material furnished with such properties is applied to a
portable wireless telephone, the portable wireless telephone is allowed to
prevent the emission or reception of any unnecessary radio waves, whereby
the telephone is hardly influenced by environmental noises. As a result,
the telephone enables communication within manufacturing factories or
automobiles which include a great deal of noises, and can diminish trouble
of malfunction of medical equipments in general hospitals in which
electronic machines or facilities of high performance are located.
In the manufacturing method according to the present invention, the
mechanical properties and air permeability of the self-tuning material can
be adjusted by changing the quality and configurations of the metallic
chips and the bonding materials, the mixing ratio of the metallic chips
and the bonding materials with each other, the pressure which is exerted
upon the metallic chips and the bonding materials while the metallic chips
and the bonding materials are heated, the temperature of the heating
operation accompanied by the pressurizing operation to the metallic chips
and the bonding materials, and other conditions on which the self-tuning
materials are manufactured. This achieves manufacturing of the self-tuning
materials which are suitable for the applicable frequencies of radio or
wireless communication devices.
The application of this method according to the present invention can
freely provide for either of the self-tuning materials in the form of
simple continued bodies of the metallic chips which are relatively low in
their strength, and those which are porous sintered bodies of high
mechanical strength.
The resin from which the bonding materials are made to form the bonding
material may be increased in the additive amount thereof to allow the
self-tuning material to be transformable.
Therefore, it is preferable that the self-tuning materials in the form of
simple continued bodies of the metallic chips are applied to portions of
radio or wireless communication devices which do not require the
self-tuning materials to be furnished with mechanical strength, and the
self-tuning materials comprising the porous sintered bodies are used for
radio or wireless communication devices which are operated in severe
service environments of, for example, high temperatures and high humidity.
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